Hi OP I’m so sorry for your loss, and very sorry about the circumstances, how awful for you. Well done for doing your best to revive your mum.
I did CPR on someone last summer, a complete stranger who collapsed and stopped breathing. It was awful, even though she (amazingly) actually started breathing and recovered eventually.
I got multiple daily flashbacks for around 2 months of her mouth and teeth, and the vomit afterwards. I did a lot of proactive stuff like talk to a counsellor, talk to friends and family etc. but found it hard to really go into details and found it didn’t really help unfortunately.
One thing I’d really recommend is calling the British heart foundation. They have something called Heart Helpline where you can speak to a cardiac nurse if you have done CPR. Speaking to someone who had experience of CPR and the various outcomes was so helpful, and normalised all of the feelings I was having. She pointed out that, as professionals, medics debrief (informally or formally) after a CPR episode, but members of the public obviously don't get that.
here is the link: https://www.bhf.org.uk/informationsupport/heart-helpline
i don’t get flashbacks often now, so they did lessen over time and speaking to the cardiac nurses really helped because they knew exactly what the sights/sounds/smells were like.
I know it will be different for you because it’s your mum, but I wanted you to know that it’s totally normal (if horrible). If you feel up to calling the helpline or speaking to someone else medical (e.g. your GP) they might be able to talk it through with you and help you put those details to rest.
💐 and un-mumsnetty hugs for you OP.